Any wheel can be stepped i.e. its setting increased at each revolution of
This will not of course be confused with the ordinary motion of the wheels
at a fixed setting. It should be noticed that increasing settings imply that the
patterns move backwards relative to Z. Any number of wheels may be stepped
(c) Stepping Switches
Each wheel has two 3-way switches in the control panel, one in the upper
row, one in the lower.
Either of these two switches may be thrown up or down.
Upper switch up ) causes the wheel to step fast
or Upper switch down ) i.e. to step at each tape
or Lower switch down ) revolution.
Lower switch up - causes the wheel to step slowly i.e. to step only
when a wheel whose lower switch is thrown down reached the plug in the setting
jacks. If in some frenzied fantasy, several wheels have their lower switches
down each of them will step a slow stepping wheel.
(d) Repeat Light
When all wheels return to their original settings (strictly to the plug in
the setting jack), the repeat light glows. A wheel whose upper switch is thrown up
Any pattern, except a "special pattern" is available deltaed either on the Q
panel (by throwing the Q selection switch to delta) or on the plug panel (by using
deltaed output jacks).
The conventional Tunny delta is the sum of present and future i.e. forwards.
Colossus deltas by remembering and adding the letter one place back i.e.
This is immaterial provided that all patterns in use are deltaed by Colossus
or all not deltaed by Colossus; but if some are and some not, then those which
are, are recorded by Colossus as one place back.
For example suppose that Z is a plain Z tape which is being deltaed by
Colossus and added to delta X set up deltaed on the X trigger, the two patterns
being level so that the recorded setting is 01.
Opposite the second sprocket hole Colossus produces for delta Z: 1st character
+ 2nd character.
Opposite the second sprocket hole delta X is plugged as: 2nd character + 3rd
It follows that the true setting of X is 02.
This is in many cases corrected by adjusting the settings, whence the phrase